One of the biggest clues to finding evidence of life on Mars – past or present – has been the existence of methane, an organic compound that is the principal component of natural gas here on Earth. Methane can arise via both biological and non-biological processes, but in both cases it can be used as “food” for living organisms (known as methanotrophs.) Methane has been detected on Mars today by both orbiting spacecraft and rovers on the ground, and now researchers have identified methane within meteorites found on Earth that originated from the Red Planet.

From a Yale news release:

The researchers examined samples from six meteorites of volcanic rock that originated on Mars. The meteorites contain gases in the same proportion and with the same isotopic composition as the Martian atmosphere. All six samples also contained methane, which was measured by crushing the rocks and running the emerging gas through a mass spectrometer. The team also examined two non-Martian meteorites, which contained lesser amounts of methane.

NASA’s Curiosity rover detected methane spikes in Gale Crater using its SAM instrument over a two-month span in late 2013 and 2014.

While these findings don’t point directly to life, they do indicate an environment in which some forms of life could survive.

“Even if Martian methane does not directly feed microbes, it may signal the presence of a warm, wet, chemically reactive environment where life could thrive,” said study co-author Sean McMahon, a postdoctoral associate at Yale University’s Department of Geology and Geophysics.

Of the over 60,000 meteorites found on Earth, only 124 have been positively identified as originating from the planet Mars. Knocked into space through an impact event these pieces of Mars landed on Earth millions of years later, to be found by scientists and both amateur and professional rock hunters around the world. They are invaluable to researchers who can use them to study the composition of Mars’ crust directly.

Sources: Yale University news and JPL